Abstract: In a digital speech interpolation system, speech inactivity time is utilized to reduce the bit rate on a link between transmitter and receiver by compressing digital characters from a plurality of trunks onto a lesser plurality of channels. If the number of trunks having active speech samples exceeds the number of channels, an overload may exist. To mitigate overload, it is common to truncate one or more bits from a transmitted character. However, bit truncation leads to signal degradation. Of course, it is desirable to abate the degradation consistent with mitigating the overload. Unfortunately, the number of bits truncated from a character on a first trunk is typically more or less than the number of bits truncated from a character on a second trunk. As a result, the signal degradation may not be uniform. To obtain a more uniform signal degradation, the instant priority rotation arrangement rotates the starting point for assigning bits to a digital frame responsive to the activity status of the trunks.

Abstract: In a communications system such as a time assignment speech interpolation (TASI) system for concentrating signals from N trunks onto C channels (C < N), and for expanding same, it is common for a speech signal to pass through a plurality of transmitter/receiver terminals, perhaps connected for tandem operation. Unfortunately, transmitter speech detector clipping of the speech signal leads to a distortion accumulation problem. Also, while a calling trunk is inactive, an inserted noise signal is commonly furnished by a receiver to the called trunk to avoid an aural "too quiet" condition. Unfortunately, actual calling trunk noise and the called trunk inserted noise may differ, leading to a noise signal contrast problem. To mitigate the signal contrast problem, communications apparatus including an improved noise signal inserting arrangement, responsive to a measure of calling trunk noise, supplies an adaptively adjusted, deterministic, pseudorandom noise signal to the called trunk.

Abstract: In a PCM system, character compression using nearly instantaneous companding (NIC) is known to obtain a reduction in the number of bits transmitted. Unfortunately, in tandem digital PCM-to-NIC-to-PCM conversions, a signal delay results because a maximum segment value is usually unknown until a block of PCM characters, which are to be converted to make up a block of NIC characters, has been received. Further, if the PCM block is received out-of-phase, a signal degradation may result because the incorrect maximum sgement value may be used during a subsequent conversion. To mitigate delay, the disclosed processor discards certain least significant bits of a PCM character and substitutes therefor a predetermined bit pattern corresponding to the difference between the maximum segment value and the segment value of the first character of the block.

Abstract: A digital speech interpolation (DSI) system advantageously utilizes speech inactivity time to reduce the bit rate by compressing digital characters from a plurality of trunks onto a lesser plurality of channels. A signaling arrangement is typically employed therein to signal a receiver as to the activity of a trunk. If the number of active trunks exceeds the number of channels, an overload may exist. Known arrangements for mitigating overload typically include apparatus responsive to an activity signal for truncating one or more bits from the digital characters and for transmitting the truncated characters. Unfortunately, quantization noise is increased and digital precision decreased in such arrangements. The hereindisclosed system includes an improved automatically adaptive arrangement for advantageously incorporating nearly instantaneous companding (NIC) and priority trunk rotation in a plurality of frames, called a multiframe.

Abstract: A digital processor apparatus is described which operates upon nonuniformly encoded digital words each one of which has .mu.-law encoded format of a sign bit to indicate polarity, segment bits to indicate range, and interval bits to indicate the location of the sample within the segment. A predetermined number of the digital words is stored in shift registers while the apparatus determines the maximum segment value represented in that block of predetermined number of words. The interval bits for one of the stored digital words are stored in a shift register along with a bit whose value is determined from the segment bits for that word. This shift register is then shifted by an amount which is dependent on the difference between the segment value for the digital word under consideration and the maximum segment value for that block of digital words.